Scanning probe microscopes (SPMs) have been known as a technique of measuring a fine three-dimensional shape. Among the scanning probe microscopes, anatomic force microscope (AFM) is an observation technique of scanning a surface of a sample while keeping a contact force at a very small value by controlling a probe with a pointed tip, and is widely used as a technique measurable for a fine three-dimensional shape on the order of atom. However, this atomic force microscope cannot measure optical properties, such as reflectance distribution and refractive-index distribution, of the surface of the sample.
Meanwhile, employment of a strained silicon for an ultra-micro semiconductor device of a 45-nm node and beyond has been planed for achieving high speed, and measurement of stress distribution in a minute region is absolutely necessary for yield management. Also, for further microfabrication, it is required to finely manage a state of impurity-atom distribution by a resolution on the order of nanometers. Physical property information such as stress distribution and impurity distribution cannot be measured by an atomic force microscope or a critical-dimension scanning electron microscope (CD-SEM) used for dimension management. While an optical method such as Raman spectroscopy has been studied, a conventional Raman microscope does not have enough spatial resolution.
Also, in order to specify a cause for occurrence of foreign particles detected in foreign-particle inspection or defects detected in defect inspection, operations for classifying the foreign particles and defects are performed by an electron microscope called a review SEM. However, since this method relies only on their shape and profile information, classification performance of the method has approached to its limit. Although improvement of this classification performance can be expected by adding optical information also in the method, a conventional optical microscope or laser scanning microscope does not have enough spatial resolution after all.
As means to measure optical-property and physical-property information of the surface of the sample with high resolution to solve these problems, a scanning near-field optical microscope (SNOM) is known. As disclosed in Japanese Journal of Applied Physics, Vol. 31, pp. L1302-L1304, 1992 (Non-Patent Document 1), this microscope measures optical properties, such as reflectance distribution and refractive-index distribution, of the surface of the sample with a resolution of several tens of nm equal to an aperture size over an optical diffraction limit by scanning the near-field light leaking from a fine aperture of several tens of nm as keeping a distance between the aperture and the sample by the same several tens of nm (aperture probe). As a similar method, Optics Letters, Vol. 19, pp. 159-161, 1994 (Non-Patent Document 2) discloses a method (scattering probe) of irradiating external light to a metal probe and scanning near-field light having a magnitude of several tens of nm scattered at a micro-tip portion of the probe.
Further, Journal of the spectroscopical research of Japan, Vol. 54, No. 4, pp. 225-237, 2005 (Non-Patent Document 3) discloses that surface plasmon excited on a metal surface by fine spot light propagates through the metal surface.
Still further, Japanese Patent Application Laid-Open Publication (Translation of PCT Application) No. 2006-515682 (Patent Document 1) discloses a method of forming fine spot light by providing a fine spherical lens at a fiber tip.
Still further, Japanese Patent Application Laid-Open Publication No. 2002-267590 (Patent Document 2) discloses a method of obtaining fine spot light by filling a metal carbide made of V, Y, Ta, Sb, or others having photoluminescence or electroluminescence characteristics, a ZnS fluorescent material, or a CaS fluorescent material inside a carbon nanotube.